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arXiv · 2602.09468

Resources of the advantage in quantum illumination: Discord and entanglement

Mojtaba Asadollahi·Mohammad Hossein Zarei
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Abstract

We investigate how the quantum advantage in quantum illumination is determined by an interplay between entanglement and discord of the probe state. In particular, we consider a setup in which the probe is a maximally mixed marginal (MMM) state and the environmental state is completely mixed where the quantum advantage equals the amount of discord consumed for illumination. We perform a conditional extremal analysis to consider the relation between the advantage and entanglement of formation and the standard measure of quantum discord in the probe state. We demonstrate that for states with fixed initial discord, the maximum (and not minimum) entanglement increases by increment of the advantage. On the other hand, for states with identical initial entanglement, we show that the minimum (and not always maximum) discord scales monotonically with advantage. These results imply that higher discord and higher entanglement in MMM states are necessary and sufficient resources for higher advantage, respectively. We also repeat our analysis with other measures of quantum correlation. In particular, we show that relative entropy of entanglement, Bures measure of entanglement and geometric discord lead to the same conclusion about the role of entanglement and discord for quantum illumination. The consistency of our results across multiple conceptually distinct measures indicates that the observed resource-advantage relation is not an artifact of a specific quantifier, but a robust feature of the protocol within the family of MMM states. We finally find a persistent linear dependence of the advantage on initial discord in the high-noise regime of the probe device, highlighting discord as the key resource for resilience to noise in the protocol.

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Mojtaba Asadollahi, Mohammad Hossein Zarei. 2026-06-30. Resources of the advantage in quantum illumination: Discord and entanglement. https://arxiv.org/abs/2602.09468

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